In many M.G.L. c. 40A, § 17, appeals, courts are required to interpret the local zoning bylaw or ordinance to address the underlying substantive issue. The judge's standard of review in these cases must give "substantial deference" to a board's reasonable interpretation of its zoning code. However, erroneous interpretations, are not entitled to deference. And it is interesting to see how this dynamic plays out both during a case and after the fact. The recent case of Mauri v. Zoning Bd. of Appeals of Newton, 83 Mass. App. Ct. 336 (2013) (on appeal from the Land Court) provides a good example.